Reforming process

ABSTRACT

A process for reforming a naphtha feedstock is disclosed. The reforming process is effected at reforming conditions in contact with a catalyst comprising a platinum group metal component and a Group IV-A metal component composited with an alumina support wherein said support is prepared by admixing an alpha alumina monohydrate with an aqueous ammoniacal solution having a pH of at least about 7.5 to form a stable suspension. A salt of a strong acid, e.g., aluminum nitrate, is commingled with the suspension to form an extrudable paste or dough. On extrusion, the extrudate is dried and calcined to form said alumina support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of a copending applicationSer. No. 880,749 filed Feb. 23, 1978 and now abandoned, which is in turna continuation-in-part of a copending application Ser. No. 788,376 filedApr. 18, 1977 now U.S. Pat. No. 4,098,874. Another related applicationis Ser. No. 788,375, which was also filed on Apr. 18, 1977, and issuedas U.S. Pat. No. 4,104,154 on Aug. 1, 1978.

This invention relates to a process for the catalytic reforming of agasoline boiling range petroleum feedstock to improve the octane ratingthereof--a process well known to the petroleum refining industry. Theprocess is effected in contact with an alumina-supported catalystcomprising a platinum group metal component. Alumina, especiallyactivated alumina, has been widely accepted as a catalyst, and morefrequently as a catalyst support or carrier material, to effect varioushydrocarbon conversion processes generally associated with petroleumrefining. In particular, virtually all of the catalysts concurrently inuse to effect the reforming process contain alumina as a major componentand comprise a platinum group metal composited with and supported on thealumina.

One of the more useful and far less costly methods of preparing thealumina in an acceptable particulate form comprises extruding thealumina in the form of a paste or dough--an alpha-alumina monohydratebeing particularly adapted to the extrusion process. In the moreconventional extrusion methods, it is the practice to admix a finelydivided form of the alumina with a peptizing agent and sufficient waterto form a paste or dough of extrudable consistency. It has been observedthat the wet powdered form of the alumina is easily extruded providedthat little if any work has been exerted on it. However, a uniform pasteor dough so essential to product strength and the productreproducibility is not as readily achieved. It is contemplated that thisis largely the result of the mixture's tendency to set to a paste ordough before the peptizing agent becomes uniformly distributed in themixture, and that the further result of the thixotropic nature of thedough or paste and its tendency toward localized sol formation underconditions of intense mixing.

It is an object of this invention to present a novel method of preparingreproducible uniform alumina extrudate particles, and to present astable catalytic reforming process utilizing said alumina as a majorcomponent of the reforming catalyst.

In one of its broad aspects, the present invention embodies a reformingprocess which comprises contacting a naphtha feedstock at reformingconditions with a catalyst comprising from about 0.01 to about 2 wt.%platinum group metal and from about 0.01 to about 5 wt.% Group IV-Ametal composited with an alumina support prepared by admixing a finelydivided alpha alumina monohydrate with an aqueous ammoniacal solutionhaving a pH of at least about 7.5 and forming a stable suspension,commingling a metal salt of a strong acid with said suspension andconverting the suspension to an extrudable paste or dough, extruding thepaste or dough, drying and therefore calcining the extruded alumina at atemperature of from about 450° to about 850° C.

One of the more specific embodiments relates to a process for reforminga naphtha feedstock which comprises contacting said feedstock atreforming conditions with a catalyst comprising from about 0.01 to about2 wt.% platinum and from about 0.01 to about 2 wt.% germanium compositedwith an alumina support wherein said support is prepared by admixing afinely divided alpha alumina monohydrate with an aqueous ammoniacalsolution having a pH of at least about 7.5 and forming a stablesuspension, commingling an alumina salt of a strong acid with saidsuspension and converting the suspension to an extrudable paste ordough, extruding the paste or dough, drying, and thereafter calciningthe extruded alumina at a temperature of from about 450° to about 850°C.

A still more specific embodiment concerns the reforming process whichcomprises contacting a naphtha feedstock at reforming conditions with acatalyst comprising from about 0.01 to about 2 wt.% platinum and fromabout 0.01 to about 2 wt.% germanium composited with an alumina supportwherein said support is prepared by admixing a finely divided alphaalumina monohydrate with an aqueous ammoniacal solution having a pH offrom about 7.5 to about 8.5 and forming a stable suspension, comminglingsufficient aluminum nitrate with said suspension to provide from about 2to about 10 wt.% of the alumina product, and converting the suspensionto an extrudable paste or dough, extruding the paste or dough, drying,and thereafter calcining the extruded alumina at a temperature of fromabout 550° to about 750° C. to provide a surface area of from about 165to about 215 m² /g and a pore volume of from about 0.3 to about 0.4 cc/gin a pore diameter range of from about 20 to about 80 Angstroms (A).

Other objects and embodiments of the present invention will becomeapparent in the following detailed specification.

The alpha-alumina monohydrate employed herein is preferably analpha-alumina monohydrate derived from the water hydrolysis of analuminum alkoxide. More preferably, the alpha-alumina monohydrate is aproduct of the well known Ziegler process. The alpha-alumina monohydrateis thus preferably prepared stepwise starting with the reaction ofaluminum, hydrogen and ethylene. After a further polymerization stepwith ethylene, the trialkyl aluminum polymerization product is oxidizedto form an aluminum alkoxide which, on subsequent water hydrolysis,yields an alumina slurry and an alcohol product. The alumina recoveredfrom the reaction mixture is generally treated for the removal ofresidual alcohols, for example by solvent extraction, and/or steamstripping, and then dried to produce the alpha-alumina monohydrate in afinely divided state.

Pursuant to the present invention, the finely divided alpha-aluminamonohydrate is admixed with an aqueous ammoniacal solution having a pHof at least about 7.5, and preferably from about 7.5 to about 8.5. Thealpha-alumina monohydrate added to the stirred aqueous ammoniacalsolution forms a stable suspension having the consistency of a lightwhipped cream--the suspension being Newtonian in character with littleif any thixotropic or dilatant behavior.

The alumina is preferably admixed with sufficient aqueous solution toprovide an extrudable paste or dough comprising from about 30 to about60 wt.% alumina. Suitable ammoniacal solutions include solutions ofbases such as ammonium hydroxide, hydroxylamine, hydrazine,tetramethylammonium hydroxide, etc., or a strong organic amine likemethylamine, dimethylamine, ethylamine, diethylamine, propylamine,diisopropylamine, n-butylamine, t-butylamine, diisobutylamine,n-amylamine, n-hexylamine, ethylenediamine, hexamethylenediamine,benzylamine, aniline, piperizine, piperadine, and the like, the selectedbase being employed in sufficient concentration to provide a pH of atleast about 7.5, and preferably from about 7.5 to about 8.5.

With the addition of a metal salt of a strong acid to the stirredsuspension as herein contemplated, the suspension becomes very fluid fora brief period permitting the suspension to become thoroughly anduniformly mixed before setting to a firm extrudable paste. The selectedmetal salt is conveniently an aluminum salt whereby the aluminumprovides a portion of the alumina of the finished product. However, themetal salt may comprise one or more metals exhibiting a catalytic effectwith respect to one or more hydrocarbon conversion reactions wherebysaid metal or metals appear as a catalytic component of the finalalumina product. The metal salt is suitably added to the stirredsuspension as an aqueous solution thereof in an amount to providesufficient acid anions to convert said suspension to an extrudablepaste, an amount which is usually equivalent to that required to providefrom about 1 to about 10 wt.% of the metal content of the finishedproduct. Suitable metal salts of a strong acid particularly include thenitrates, sulfates and halides, and especially the nitrates, forexample, aluminum nitrate, ferric nitrate, nickel nitrate, cobaltnitrate, chromium nitrate, copper nitrate, palladium nitrate, silvernitrate, zinc nitrate, stannous and stannic nitrate and the like.

Extrusion of the paste or dough can be effected in accordance with priorart practice. Thus, utilizing a conventional screw type extruder, thedough or paste is processed through a die plate generally comprisingorifice openings in the 1/32-1/4" diameter range. The freshly extrudedmaterial may be collected in the form of strands of indefinite or randomlengths to be dried and subsequently broken into extrudate particles; orthe freshly extruded material may be cut into random or predeterminedlengths and subsequently dried; or the freshly extruded material may beformed into spheres, for example, by the process whereby the extrudatestrands are collected in a spinning drum--the strands becoming segmentedand spheroidized under the spinning influence of the drum.

In any case, the extrudate is dried and subsequently calcined. Suitabledrying is accomplished at a temperature of from about 100° to about 120°C. in an air atmosphere using a forced draft oven. The extrudate productcan be dried and calcined at a temperature of from about 450° to about850°, but preferably at a temperature of from about 550° to about 750°C. in a flow of air containing 1 to 5 wt.% steam to produce a calcinedproduct having a surface area of from about 165 to abouyt 215 m² /g anda pore volume of from about 0.3 to about 0.4 cc/g in the pore diameterrange of from about 20 to about 80 A.

The alumina composition of this invention is advantageously employed asa support or carrier material for other catalytic components to promotevarious hydrocarbon conversion reactions including dehydrogenation ofspecific hydrocarbons or petroleum fractions, isomerization of specifichydrocarbons or petroleum fractions, hydrocracking of lower molecularweight hydrocarbons such as occur in the kerosene and gas oil boilingrange, and the oxidation of hydrocarbons to provide first, second andthird stage oxidation products. Reaction conditions employed in thevarious hydrocarbon conversion reactions are those heretofore practiced.For example, alkylaromatic isomerization reaction conditions include atemperature of from about 0° to about 535° C., a pressure of from aboutatmospheric to about 1500 psig., a hydrogen to hydrocarbon mole ratio offrom about 0.5 to about 20, and a liquid hourly space velocity (LHSV) offrom about 0.5 to about 20. Likewise, a typical hydrocracking operationis effected at a pressure of from about 500 to about 1500 psig., atemperature of from about 200° to about 500° C., an LHSV of from about 4to about 10, and a hydrogen circulation rate of from about 1000 to about10,000 standard cubic feet per barrel (SCFB) of hydrocarbon charge.

The alumina composition of this invention is useful as a support orcarrier material for a platnum group metal component to yield animproved reforming catalyst as taught in the aforementioned U.S. Pat.No. 4,098,874. See also U.S. Pat. No. 4,104,154 filed concurrentlytherewith. The alumina composition of this invention is of particularadvantage as a support or carrier material for a platinum group metalcomponent in combination with a Group IV-A metal component to yield animproved reforming catalyst. The platinum group metal component issuitably composited with the support or carrier material by impregnationand/or ion-exchange techniques familiar to the art. For example, asoluble platinum group compound, that is, a soluble compound ofplatinum, palladium, rhodium, ruthenium, osmium and/or iridium, isprepared in an aqueous solution, and the alumina particles soaked,dipped, or otherwise immersed therein. Suitable platinum group compoundsinclude platinum chloride, chloroplatinic acid, ammoniumchloroplatinate, dinitrodiamino platinum, palladium chloride, and thelike. It is common practice to impregnate the support or carriermaterial with an aqueous chloroplatinic acid solution acidified withhydrochloric acid to facilitate an even distribution of platinum on thesupport or carrier material. The support or carrier material ispreferably maintained in contact with the impregnating solution atambient temperature conditions, suitably for at least about 30 minutes,and the impregnating solution thereafter evaporated to dryness. Forexample, a volume of the particulate support or carrier material isimmersed in a substantially equal volume of impregnating solution in asteam jacketed rotary dryer and tumbled therein for a brief period atabout room temperature. Steam is thereafter applied to the dryer jacketto expedite evaporation of the impregnating solution and recovery ofsubstantially dry impregnated particles.

As heretofore stated, the alumina composition of this invention isuseful as a support or carrier material for a platinum group metalcomponent in combination with a Group IV-A metal component, i.e.,germanium, tin and/or lead. The germanium, tin and/or lead component maybe composited with the support or carrier material in any conventionalor otherwise convenient manner. Suitable methods include impregnationand/or ion-exchange of the support or carrier material with a suitablecompound of one or more of said components in any desired sequence, withor without intermediate calcination. In the impregnation of the supportor carrier material, it is a preferred practice to impregnate one ormore of said components on said support or carrier materialsimultaneously with the platinum group metal component from a commonimpregnating solution. For example, when the added component is tin,stannic chloride is conveniently and advantageously prepared in commonsolution with chloroplatinic acid, the concentration of each componenttherein being sufficient to yield a catalyst product containing fromabout 0.01 to about 2.0 wt.% platinum and from about 0.1 to about 5.0wt.% tin calculated as the elemental metal. Similarly, when the desiredadded component is germanium, germanium tetrachloride and chloroplatinicacid can be prepared in a common aqueous and/or alcoholic solution toimpregnate the support or carrier material, suitably with from about0.01 to about 2.0 wt.% platinum and from about 0.01 to about 2.0 wt.%germanium. Thus, another embodiment of this invention concerns analumina support or carrier material characterized by a surface area offrom about 165 to about 215 m² /g and a pore volume of from about 0.3 toabout 0.4 cc/g in the pore diameter range of from about 20 to about 80A, said alumina being impregnated with from about 0.01 to about 2.0 wt.%platinum and from about 0.01 to about 2.0 wt.% germanium.

The Group IV-A metal component, and particularly the germanium and tincomponents, is advantageously composited with the alumina by including asuitable acid salt thereof in the aforementioned suspension prepared byadmixing a finely divided alpha-alumina monohydrate with an aqueousalkaline solution. For example, an acid salt of tin such as stannous orstannic chloride, may be admixed with said suspension and serve not onlyas a precursor of the desired tin component, but also as the metal saltof a strong acid as herein contemplated. Following the extrusion processand subsequent calcination, the alumina is obtained comprising the tincomponent in intimate combination therewith and suitable for furtherimpregnation and/or ion-exchange to incorporate, for example, theplatinum group metal component.

The final catalyst composite generally will be dried at a temperature offrom about 95° to about 315° C. for a period of from about 2 to about 24hours or more, and finally calcined at a temperature of from about 375°to about 595° C. in an air atmosphere for a period of from about 0.5 toabout 10 hours in order to convert the catalytic component substantiallyto the oxide form. Although not essential, it is preferred that theresultant calcined catalytic composite be subjected to a substantiallywater-free reduction step prior to its use in the conversion ofhydrocarbons. This step is designed to insure a uniform and finelydivided dispersion of the catalytic component throughout the carriermaterial. Preferably, substantially dry hydrogen is used as the reducingagent in this step. The reducing agent is contacted with the calcinedcatalyst at a temperature of from about 425° to about 650° C. and for aperiod of from about 0.5 to about 10 hours. This reduction treatment maybe performed in situ as part of a start-up sequence if precautions aretaken to predry the plant to a substantially water-free state and ifsubstantially water-free hydrogen is used.

The reforming of gasoline boiling range petroleum fractions to improvethe octane rating thereof is a process well known to the petroleumrefining industry. The petroleum fraction may be a full boiling rangegasoline fraction boiling in the 10°-220° C. range, although it is moreoften what is called a naphtha fraction, a gasoline fraction having aninitial boiling point of from about 65° to about 120° C. and an endboiling point of from about 175° to about 220° C. Refrorming conditionsgenerally include a pressure of from about 50 to about 1000 psig. and atemperature of from about 425° to about 595° C. The catalyst of thisinvention permits a stable reforming operation to be effected in apreferred pressure range of from about 50 to about 350 psig. utilizing ahydrogen/hydrocarbon mole ratio of from about 0.5 to about 10 and anLHSV of from about 0.5 to about 10. Preferably, a temperature of fromabout 485° to about 565° C., is employed.

The following examples are presented in illustration of certainpreferred embodiments of this invention, and in illustration of theimproved alumina catalyst support or carrier material derived from thepractice of this invention. The examples are not intended as an unduelimitation on the generally broad scope of the invention as set out inthe appended claims.

EXAMPLE I

This example is presented as representative of a related prior artreforming catalyst. In this example, 150 cc of concentrated nitric acidwas diluted to 2450 cc with water and admixed as a spray with 4000 g ofa stirred, finely divided, alpha-alumina monohydrate (Catapal SBalumina). The alumina initially contained about 25 wt.% volatile matter.After about 30 minutes of stirring, the resulting paste was extruded,oven dried for about 12 hours at 110° C., and calcined for about 2 hoursat 650° C. in air containing about 3 wt.% steam. The calcined aluminaextrudate particles had an average bulk density of 0.74 g/cc, a surfacearea of 213 m² /g, an average pore volume of 0.39 cc/g, and an averagepore diameter of 79 A. About 250 cc of the calcined alumina extrudateparticles were immersed in 250 cc of an impregnating solution preparedby admixing 46.9 cc of chloroplatinic acid (10 mg of Pt/cc), 9.5 cc ofan ethanolic solution of germanium tetrachloride (33 mg of Ge/cc), and21.3 cc of concentrated hydrochloric acid, the solution being diluted to250 cc with water. The alumina particles were tumbled in the solutionfor about 1/2 hour at room temperature utilizing a steam-jacketed rotarydryer. Steam was thereafter applied to the dryer jacket and the solutionevaporated to dryness in contact with the tumbling particles. Theparticles were subsequently calcined in air for about 1/2 hour at 200°C., and for an additional 1/2 hour at 525° C. The calcined particleswere thereafter reduced in hydrogen for about 1 hour at 565° C. to yielda catalyst comprising about 0.25 wt.% platinum, 0.17 wt.% germanium, andabout 1.0 wt.% chloride. The catalyst of this example is hereinafterreferred to as Catalyst A.

EXAMPLE II

In this example, representative of one preferred embodiment of thisinvention, 4000 g of a finely divided alpha-alumina monohydrate (CatapalSB alumina) was added to a rapidly stirred aqueous alkaline solutionhaving a pH of about 7.5. The alumina contained about 25 wt.% volatilematter, and the alkaline solution consisted of 12.9 cc of concentratedammonium hydroxide diluted to 3450 cc with water. The resulting slurrywas a stable suspension having a light creamy consistency. Thesuspension was Newtonian in character and gave no indication ofthixotropic or dilatant behavior. After about 30 minutes of continuousstirring, an aluminum nitrate solution was added, the solutionconsisting of 595 g of Al(NO₃)₃ 9H₂ O dissolved in 1400 cc of water. Thestirred suspension became very thin and extremely fluid for about 10seconds and thereafter set to a thick paste with a solids content ofabout 33 wt.%. The paste was subsequently extruded, oven dried for about12 hours at 110° C., and calcined for about 2 hours at 650° C. in aircontaining about 3 wt.% steam. The dried and calcined alumina producthad a surface area of 206 m² /g, and a pore volume of about 0.39 cc/g,and an average pore diameter of 76 A. About 250 cc of the calcinedalumina extrudate particles were subsequently impregnated with aplatinum and germanium component, and dried and calcined, allsubstantially in accordance with the method of Example I. The catalystthus comprised about 0.22 wt.% platinum, 0.15 wt.% germanium and about 1wt.% chloride. The average bulk density of the catalyst wasapproximately 0.84 g/cc. The catalyst of this example is hereinafterreferred to as Catalyst B.

The catalysts thus prepared were evaluated in a laboratory scalereforming plant comprising a reactor, a hydrogen separator and adebutanizer column. A hydrogen-rich recycle stream and the hydrocarboncharge were commingled and preheated to a desired temperature, thehydrocarbon charge being a naphtha fraction characterized by an APIgravity at 15.5° C. of 66.4 and F-1 clear octane rating of 40, and an85°-182° C. boiling range. A hydrogen-hydrocarbon mixture was passeddownflow through a fixed catalyst bed contained in the reactor. Thereactor effluent was passed through a high pressure-low temperatureseparator wherein a hydrogen-rich gaseous phase was separated from theliquid phase at a pressure of about 300 psig. and a temperature of about13° C. A portion of the gaseous phase was continuously recycled to thereactor through a high surface area sodium scrubber, and the excess overthat required to maintain plant pressure was recovered as excessseparator gas. The liquid phase was continuously withdrawn from theseparator and passed to the debutanizer column where light ends weretaken overhead as a debutanizer gas, and a C₅ + reformate productrecovered as bottoms.

The catalyst was evaporated over ten test periods, each comprising a12-hour line-out followed by a 12-hour test period. The reactortemperature was periodically adjusted to maintain a 100 RON (researchoctane number) clear C₅ + product. Reforming conditions further includedan LHSV of 2.0, a reactor outlet pressure of 300 psig., and ahydrogen/hydrocarbon mole rato of about 2.5. The test results aretabulated below (Table I) for each test period in terms of the liquidvolume percent C₅ + yield, mole percent hydrogen in the excess separatorgas and reactor block temperature required to maintain a 100 RONproduct.

                  TABLE I                                                         ______________________________________                                               Reactor   Recycle Gas C.sub.5 + Yield                                         Temp. °C.                                                                        Mole % H.sub.2                                                                            L.V. %                                           Period No.                                                                             Cat A.  Cat B   Cat A Cat B Cat A Cat B                              ______________________________________                                        1        511     507     76.9  77.8  73.5  73.2                               2        512     511     77.5  77.3  74.8  73.6                               3        516     515     77.5  76.2  74.2  72.6                               4        519     517     76.2  76.9  73.4  73.0                               5        519     518     77.1  76.8  73.8  72.8                               6        522     519     76.1  77.3  73.0  72.9                               7        526     520     74.4  77.6  71.6  72.9                               8        529     522     74.6  77.1  71.3  72.6                               9        530     523     75.5  76.8  71.0  72.6                               10       531     524     74.2  75.7  70.6  72.1                               ______________________________________                                        In particular, the tabulated data demonstrates an activity advantage, and     a decided improvement in activity and selectivity stability, to be            derived from the platinum-germanium combination impregnated on the            extruded alumina support of this invention. EXAMPLE III -About 350 cc of      the calcined alumina extrudate particles of Example I were immersed in        350 cc of an impregnating solution prepared by admixing 68.2 cc of            chloroplatinic acid (10 mg Pt/cc), 27.3 cc of perrhenic acid (25 mg           Re/cc) and 26.8 cc of concentrated hydrochloric acid, the solution being      diluted to 350 cc with water. The alumina particles were tumbled in the       solution for about 1/2 hour at room temperature utilizing a                   steam-jacketed rotary dryer. Steam was thereafter applied to the dryer        jacket and the solution evaporated to dryness in contact with the             tumbling particles. The impregnated particles were thereafter calcined        and reduced in hydrogen as in the previous examples. The catalyst product     contained 0.26 wt.% platinum, 0.26 wt.% rhenium, and about 1 wt.%             chloride. The catalyst of this example is hereinafter referred to as          Catalyst C. EXAMPLE IV -In this example, an impregnating solution as          described in Example III was employed to impregnate calcined alumina          extrudate particles prepared in accordance with the preparation of            Example II. Thus, about 350 cc of the calcined alumina extrudate              particles were immersed in 350 cc of the impregnating slution. The            particles were tumbled in the solution of about 1/2 hour at room              temperature utilizing a steam-jacketed rotary dryer. Steam was thereafter     applied to the dryer jacket and the solution evaporated to dryness in         contact with the tumbling particles. The impregnated particles were           subsequently calcined in air and reduced in hydrogen all in accordance        with the previous examples. The catalyst product contained 0.23 wt.%          platinum, 0.23 wt.% rhenium, and about 1 wt.% chloride. The catalyst of       this example is hereinafter referred to as Catalyst D. -The catalysts of      Examples III and IV were evaluated in the described laboratory scale          reforming plant at the described conditions. The results are set out in       Table II below.                                                           

    TABLE II                                                                      ______________________________________                                               Reactor   Recycle Gas C.sub.5 + Yield                                         Temp. °C.                                                                        Mole % H.sub.2                                                                            L.V. %                                           Period No.                                                                             Cat C   Cat D   Cat C Cat D Cat C Cat D                              ______________________________________                                        1        509     508     72.2  66.9  70.0  69.1                               2        511     512     72.5  68.1  70.3  68.8                               3        512     514     71.2  68.6  69.8  68.3                               4        513     514     71.1  70.5  69.9  70.0                               5        515     516     69.6  69.9  69.3  69.6                               6        517     518     72.1  66.7  69.4  69.4                               7        519     519     71.4  68.8  68.8  69.5                               8        519     519     71.5  70.4  69.4  70.2                               9        520     519     72.1  70.5  69.7  70.1                               10       521     524     71.5  69.4  69.8  69.6                               ______________________________________                                    

While the tabulated data indicates that the catalysts of Examples IIIand IV which embody the platinum-rhenium combination are substantiallyequivalent, this only serves to highlight the unexpected improvement inactivity, activity stability and selectivity stability demonstrated bythe platinum-germanium combination impregnated on the extruded aluminasupport of this invention.

We claim as our inventon:
 1. A process for reforming a naphtha feedstockwhich comprises contacting said feedstock at reforming conditions with acatalyst comprising from about 0.01 to about 2 wt.% platinum group metaland from about 0.01 to about 5 wt.% Group IV-A metal selected from thegroup consisting of germanium and tin composited with an alumina supportprepared by admixing a finely divided alpha-alumina monohydrate with anaqueous ammoniacal solution having a pH of at least about 7.5 andforming a stable suspension, commingling a metal salt of a strong acidwith said suspension and converting the suspension to an extrudablepaste or dough, extruding the paste or dough, drying, and thereaftercalcining the extruded alumina at a temperature of from about 450° toabout 850° C.
 2. The process of claim 1 further characterized in thatsaid platinum group metal is platinum.
 3. The process of claim 1 furthercharacterized in that said alumina is a water hydrolysis product of analuminum alkoxide.
 4. The process of claim 1 further characterized inthat said alumina is a water hydrolysis product of an aluminum alkoxideproduced by the Ziegler process.
 5. The process of claim 1 furthercharacterized in that said aqueous ammoniacal solution has a pH of fromabout 7.5 to about 8.5.
 6. The process of claim 1 further characterizedin that said metal salt of a strong acid is an aluminum salt of a strongacid.
 7. The process of claim 1 further characterized in that said metalsalt of a strong acid is aluminum nitrate.
 8. The process of claim 1further characterized in that said metal salt of a strong acid is analuminum salt of a strong acid employed in an amount to provide fromabout 2 to about 10 wt.% of the alumina in the final product.
 9. Theprocess of claim 1 further characterized in that said suspensioncomprises from about 30 to about 60 wt.% alumina.
 10. The process ofclaim 1 further characterized in that said alumina is calcined at atemperature of from about 550° to about 750° C. to provide a surfacearea of from about 165 to about 215 m² /g, and a pore volume of fromabout 0.3 to about 0.4 cc/g in a pore diameter range of from about 20 toabout 80 Angstroms.